This application claims priority to JP 2013-214084 filed in Japan on Oct. 11, 2013, the entire disclosure of which is hereby incorporated by reference in its entirety.
The present invention relates to an electrical connection box that mounts to a vehicle or the like, and in particular relates to an electrical connection box formed by a second case assembled beneath a first case.
Conventionally, in a vehicle or the like, an electrical connection box such as a junction box or a relay box is used. For example, as disclosed in Japanese Patent Application Publication No. 2006-345616, an electrical connection box is formed by a lower cover as a second case assembled beneath a box main body as a first case.
There are electrical connection boxes positioned at locations, such as an engine compartment, where water can penetrate during rain or during a carwash. With the conventional electrical connection box, as also disclosed by Japanese Patent Application Publication No. 2006-345616, the waterproofing properties are ensured by placing an outer wall of the box main body positioned above on an outer side of an outer wall of a lower cover positioned below, such that the box main body covers the lower cover.
However, with the structure as disclosed in Japanese Patent Application Publication No. 2006-345616, during for example a car wash, when water is applied at high pressure, water enters through the space between the outer wall of the box main body and the outer wall of the lower cover, and the waterproofing properties are insufficient. In particular, there is the problem that the space between the outer wall of the box main body and the outer wall of the lower cover, which becomes the path of ingress for water, extends vertically and opens vertically inside of the box body such that water entering the space sprays upward inside the box main body, easily hitting electrical components inside the box body.
Thus, Japanese Patent Application Publication No. 2013-34320 discloses providing the box main body with an inner wall (reference numeral 33) extending downward at the inner side of the lower cover, and by having the path of ingress for water open downward inside the box body, water which has penetrated into the box main body is evacuated downward. However, the structure disclosed by Japanese Patent Application Publication No. 2013-34320 still cannot be said to be a sufficient preventative measure because water is not actually prevented from penetrating through the space between the box main body and the lower cover, and when a large amount of water has penetrated it is likely that the water will spray inside the box main body due to vibrations while driving.